U.S. patent application number 15/025190 was filed with the patent office on 2016-08-18 for spectacle lens for a display device that can be fitted on the head of a user and generates an image, and display device with such a spectacle lens.
The applicant listed for this patent is CARL ZEISS SMART OPTICS GMBH. Invention is credited to Hans-Juergen DOBSCHAL, Karsten LINDIG.
Application Number | 20160238843 15/025190 |
Document ID | / |
Family ID | 51626033 |
Filed Date | 2016-08-18 |
United States Patent
Application |
20160238843 |
Kind Code |
A1 |
DOBSCHAL; Hans-Juergen ; et
al. |
August 18, 2016 |
SPECTACLE LENS FOR A DISPLAY DEVICE THAT CAN BE FITTED ON THE HEAD
OF A USER AND GENERATES AN IMAGE, AND DISPLAY DEVICE WITH SUCH A
SPECTACLE LENS
Abstract
A spectacle lens for a display device can be fitted on the head
of a user and generate an image. The spectacle lens body can
include a front side, a rear side, a coupling-in section in an edge
area of the spectacle lens and a coupling-out section in a central
area of the spectacle lens, two opposing reflecting surfaces in the
area of the coupling-in section, and facets embedded in the area of
the coupling-in section in the spectacle lens body between the two
reflecting surfaces and arranged next to each other in the
direction from the coupling-in to the coupling-out section in a
first and an adjoining second area. The facets in the first area
can be partially reflective or reflective. The facets in the second
area can be partially reflective. Directly neighboring facets in
the second area can be connected by a partially transparent or
wholly transparent face.
Inventors: |
DOBSCHAL; Hans-Juergen;
(Kleinromstedt, DE) ; LINDIG; Karsten; (Erfurt,
DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
CARL ZEISS SMART OPTICS GMBH |
Aalen |
|
DE |
|
|
Family ID: |
51626033 |
Appl. No.: |
15/025190 |
Filed: |
September 25, 2014 |
PCT Filed: |
September 25, 2014 |
PCT NO: |
PCT/EP2014/070556 |
371 Date: |
March 25, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G02B 2027/012 20130101;
G02B 2027/0123 20130101; G02B 2027/013 20130101; G02B 27/0081
20130101; G02B 2027/0178 20130101; G02B 27/30 20130101; G02B
27/0172 20130101 |
International
Class: |
G02B 27/01 20060101
G02B027/01; G02B 27/00 20060101 G02B027/00; G02B 27/30 20060101
G02B027/30 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 27, 2013 |
DE |
10 2013 219 624.5 |
Claims
1-11. (canceled)
12. A spectacle lens for a display device that can be fitted on the
head of a user and generate an image, the spectacle lens
comprising: a spectacle lens body comprising a front side, a rear
side, and as seen in top view onto the spectacle lens, a
coupling-in section in an edge area of the spectacle lens and a
coupling-out section in a central area of the spectacle lens, and
two opposing reflecting surfaces in an area of the coupling-in
section, and a plurality of facets embedded in the area of the
coupling-in section in the spectacle lens body between the two
opposing reflecting surfaces and arranged next to each other in a
direction from the coupling-in to the coupling-out section in a
first and an adjoining second area, wherein the facets in a first
area are either partially reflective or reflective, wherein the
facets in a second area are partially reflective, wherein the
facets directly neighbouring one another in the second area are
connected by a face which is partially transparent or transparent,
wherein the spectacle lens is capable of guiding light bundles of
pixels of the generated image that are coupled into the spectacle
lens via the coupling-in section of the spectacle lens, in the
spectacle lens by reflections to the coupling-out section and
coupling them out of the spectacle lens via the coupling-out
section, wherein the facets in the first area reflect the light
bundles the facets for the coupling-in at least partially to the
second reflecting surface, wherein a reflection in the direction to
the first reflecting surface takes place for the guiding of the
light bundles, and wherein light bundles striking the faces in the
second area thereby run through the faces to the first reflecting
surface and are reflected on the first reflecting surface for the
guiding of the light bundles, and after the reflection, are
transmitted through the partially reflective facets in the second
area.
13. The spectacle lens according to claim 12, wherein the first
reflecting surface is formed by the front side.
14. The spectacle lens according to claim 12, wherein the second
reflecting surface is formed by the rear side.
15. The spectacle lens according to claim 12, wherein at least one
of the first and the second reflecting surfaces are formed between
the front and the rear side.
16. The spectacle lens according to claim 12, wherein at least one
of the first and the second reflecting surfaces are formed
flat.
17. The spectacle lens according to claim 12, wherein the
reflectivity of the first reflecting surface increases in the
direction from the coupling-in to the coupling-out section.
18. The spectacle lens according to claim 12, wherein the
reflectivity of the facets increases in the direction from the
coupling-in to the coupling-out section.
19. The spectacle lens according to claim 12, wherein at least one
of the coupling-in section and the coupling-out section have an
imaging effect.
20. The spectacle lens according to claim 12, wherein the
coupling-in section has a collimation effect.
21. A display device, comprising: a holder that can be fitted on
the head of a user; an image-generating module secured to the
holder, which generates an image; and an imaging optical system
secured to the holder, which comprises a spectacle lens according
to claim 12 and which, when the holder is fitted on the head,
images the generated image such that the user can perceive it as a
virtual image.
22. A spectacle lens for a display device that can be fitted on the
head of a user and generate an image, the spectacle lens
comprising: a spectacle lens body comprising a curved front side, a
rear side, and as seen in top view onto the spectacle lens, a
coupling-in section in an edge area of the spectacle lens and a
coupling-out section in a central area of the spectacle lens; two
opposing reflecting surfaces in the area of the coupling-out
section; and a plurality of facets, which are embedded in the area
of the coupling-out section in the spectacle lens body between the
two reflecting surfaces and arranged next to each other in the
direction from the coupling-in to the coupling-out section in a
first and an adjoining second area; wherein the facets in the first
area are partially reflective, the facets in the second area are
partially reflective or reflective and the facets directly
neighbouring one another in the first area are connected by a face
which is partially transparent or transparent, wherein the
spectacle lens is capable of guiding light bundles of pixels of the
generated image, which are coupled into the spectacle lens via the
coupling-in section of the spectacle lens, in the spectacle lens by
reflection to the coupling-out section and coupling them out of the
spectacle lens via the coupling-out section, wherein, for the
coupling-out, the facets in the first area partially reflect the
light bundles striking them for the coupling-out towards the second
reflecting surface and partially transmit them to the first
reflecting surface, where a reflection in the direction to the
second reflecting surface takes place, and wherein light bundles
striking the faces in the first area thereby run through the faces
to the second reflecting surface and are reflected on the second
reflecting surface to facets in the second area and reflected by
these towards the second reflecting surface for the coupling-out.
Description
PRIORITY
[0001] This application claims the benefit of German Patent
Application No. 02013219624.5 filed on Sep. 27, 2013, which is
hereby incorporated herein by reference in its entirety.
FIELD
[0002] The present invention relates to a spectacle lens for a
display device that can be fitted on the head of a user and
generates an image, and a display device with such a spectacle
lens.
BACKGROUND
[0003] Spectacle lenses are often formed such that light bundles of
pixels of the generated image are coupled into the spectacle lens
via a coupling-in section, guided in the spectacle lens by total
internal reflection on the front and the rear side to a
coupling-out section and deflected there such that a coupling-out
takes place via the rear side of the spectacle lens.
[0004] In the case of the coupling-in section the difficulty can
arise that after total internal reflection on the rear side an
already coupled-in or deflected bundle of beams strikes the
coupling-in section again and is there deflected in an undesired
manner such that it is converted into stray light. In order to
prevent this, the thickness of the spectacle lens would have to be
increased (for example to within the range from 10 to 20 mm), which
is, however, undesired. Alternatively, the field of view and/or the
size of the exit pupil or eyebox could be reduced, which is also
undesired, however.
SUMMARY
[0005] An object of the invention is to provide a spectacle lens
for a display device that can be fitted on the head of a user and
generates an image, with which the difficulties named above can be
overcome almost completely.
[0006] The disclosure includes a spectacle lens for a display
device that can be fitted on the head of a user and generates an
image, wherein the spectacle lens comprises a spectacle lens body
comprising a front side and a rear side, as well as, seen in top
view onto the spectacle lens, a coupling-in section in an edge area
of the spectacle lens and a coupling-out section in a central area
of the spectacle lens, two opposing reflecting surfaces in the area
of the coupling-in section and facets which are embedded in the
area of the coupling-in section in the spectacle lens body between
the two reflecting surfaces and arranged next to each other in the
direction from the coupling-in to the coupling-out section in a
first and an adjoining second area, wherein the facets in the first
area are partially reflective or reflective, the facets in the
second area are partially reflective and directly neighboring
facets in the second area are connected by a face which is
partially transparent or transparent, wherein the spectacle lens is
suitable for guiding light bundles of pixels of the generated
image, which are coupled into the spectacle lens via the
coupling-in section of the spectacle lens, in the spectacle lens by
reflections to the coupling-out section and coupling them out of
the spectacle lens via the coupling-out section, and wherein the
facets in the first area reflect the light bundles striking it for
the coupling-in at least partially to the second reflecting
surface, at which a reflection in the direction to the first
reflecting surface takes place for the guiding of the light
bundles, wherein light bundles striking the faces in the second
area thereby run through the faces to the first reflecting surface
and are reflected on the first reflecting surface for the guiding
of the light bundles and, after the reflection, transmitted through
the partially reflective facets in the second area.
[0007] Through this formation of the facets in the two areas, two
optical functions are advantageously provided in the second area.
On the one hand the light bundles which have already been coupled
into the spectacle lens by reflection on facets of the first area
for the guiding are reflected on the first reflecting surface such
that after passing through the facets of the second area (the
facets are passed through virtually from behind) they are guided in
the desired manner. On the other hand the light bundles which have
yet to be coupled in and strike facets for the first time (in this
case facets of the second area) are deflected in the desired manner
such that they are likewise guided to the coupling-out section.
[0008] Through this procedure, already coupled-in light bundles can
thus strike the second area with facets problem-free for the
coupling-in of further light bundles, with the result that the
extent of the coupling-in section in the direction of the
coupling-out section is not limited by the fact that already
coupled-in light bundles must not strike the coupling-in section
again. The entirety of all the light bundles to be coupled in can
thus have the desired large extent in the direction from the
coupling-in to the coupling-out section, in order to provide a
large field of view and/or a large extent of the exit pupil in this
direction. Naturally, the coupling-in section can also comprise a
third and further areas, which adjoin the second area and further
guide the already coupled-in light bundles, in the same way as in
the second area, in the desired manner and deflect light bundles
entering for the first time such that the desired guiding to the
coupling-out section is possible. The front side and/or rear side
of the spectacle lens body can be formed curved.
[0009] By a facet is meant, in particular, a piece of surface, a
surface element or a surface. The piece of surface, the surface
element or the surface can provide the described optical effect of
the facet.
[0010] In particular, the first reflecting surface can be formed by
the front side. Furthermore, the second reflecting surface can be
formed by the rear side.
[0011] Alternatively, it is possible for the first and/or the
second reflecting surface to be formed between the front and the
rear side. In this case, the first and/or the second reflecting
surface can also be formed flat.
[0012] The reflectivity of the first reflecting surface can
increase in the direction from the coupling-in to the coupling-out
section. The reflectivity of the facets can also increase in this
direction.
[0013] The coupling-in section and/or the coupling-out section can
have an imaging effect. Furthermore, the coupling-in section can
have a collimation effect.
[0014] The disclosure also includes a spectacle lens for a display
device that can be fitted on the head of a user and generates an
image, wherein the spectacle lens comprises a spectacle lens body
comprising a curved front side and a rear side, as well as, seen in
top view onto the spectacle lens, a coupling-in section in an edge
area of the spectacle lens and a coupling-out section in a central
area of the spectacle lens, two opposing reflecting surfaces in the
area of the coupling-out section and facets which are embedded in
the area of the coupling-out section in the spectacle lens body
between the two reflecting surfaces and arranged next to each other
in the direction from the coupling-in to the coupling-out section
in a first and an adjoining second area, wherein the facets in the
first area are partially reflective, the facets in the second area
are partially reflective or reflective and directly neighboring
facets in the first area are connected by a face which is partially
transparent or transparent, wherein the spectacle lens is suitable
for guiding light bundles of pixels of the generated image, which
are coupled into the spectacle lens via the coupling-in section of
the spectacle lens, in the spectacle lens by reflection to the
coupling-out section and coupling them out of the spectacle lens
via the coupling-out section, and wherein, for the coupling-out,
the facets in the first area partially reflect the light bundles
striking it for the coupling-out towards the second reflecting
surface and partially transmit them to the first reflecting
surface, at which a reflection in the direction to the second
reflecting surface takes place, wherein light bundles striking the
faces in the first area thereby run through the faces to the second
reflecting surface and are reflected on the second reflecting
surface to facets in the second area and reflected by the latter
towards the second reflecting surface for the coupling-out.
[0015] Through this formation of the coupling-out section, an
effective pupil expander is provided.
[0016] The spectacle lens with this coupling-out section formed as
a pupil expander can be developed in the same way as the already
described spectacle lens according to the invention. In particular,
the two spectacle lenses can also be combined in such a way that
the described facet structure of the coupling-in section is
combined with the described facet structure of the coupling-out
section.
[0017] The disclosure further includes an optical element for
guiding light bundles, which comprises a transparent body for the
light bundles with a front side and a rear side, a coupling-in
section and, spaced apart from this, a coupling-out section, two
opposing reflecting surfaces in the area of the coupling-in section
and facets which are embedded in the area of the coupling-in
section between the two reflecting surfaces and arranged next to
each other in the direction from the coupling-in to the
coupling-out section in a first and an adjoining second area,
wherein the facets in the first area are partially reflective or
reflective, the facets in the second area are partially reflective
and directly neighboring facets in the second area are connected by
a face which is partially transparent or transparent, wherein the
optical element is suitable for guiding the light bundles which are
coupled into the optical element via the coupling-in section in the
optical element by reflection to the coupling-out section and
coupling them out of the optical element via the coupling-out
section, and wherein the facets in the first area reflect the light
bundles striking it for the coupling-in at least partially to the
second reflecting surface, at which a reflection in the direction
to the first reflecting surface takes place for the guiding of the
light bundles, wherein light bundles striking the faces in the
second area thereby run through the faces to the first reflecting
surface and are reflected on the first reflecting surface for the
guiding of the light bundles and, after the reflection, transmitted
through the partially reflective facets in the second area.
[0018] Such an optical element can be developed in the same way as
the already described spectacle lenses.
[0019] In particular, the two reflecting surfaces can be formed on
the front side and the rear side. Furthermore, the reflecting
surfaces can bring about the reflection by total internal
reflection on the front and the rear side.
[0020] The facets are in particular formed such that they do not
bring about a desired diffractive effect.
[0021] The first and the second area of the coupling-in and/or the
coupling-out section preferably comprise in each case at least one,
two or more facets.
[0022] The disclosure also includes a display device, with a holder
that can be fitted on the head of a user, an image-generating
module secured to the holder, which generates an image, and an
imaging optical system secured to the holder, which comprises a
spectacle lens according to the invention and which, when the
holder is fitted on the head, images the generated image such that
the user can perceive it as a virtual image.
[0023] The imaging optical system can comprise the spectacle lens
as the only optical element. However, it is also possible for the
imaging optical system to comprise, in addition to the spectacle
lens, also at least one further optical element.
[0024] Thus, the further optical element can be e.g. a collimation
optical system which is arranged between the spectacle lens and the
image-generating module, with the result that the light bundles
from the image-generating module are coupled into the spectacle
lens as collimated bundles.
[0025] The image-generating module can in particular comprise a
two-dimensional imaging system, such as e.g. an LCD module, an LCoS
module, an OLED module or a tilting mirror matrix. The imaging
system can be self-luminous or not self-luminous.
[0026] The image-generating module can in particular be formed such
that it generates a monochromatic or a multi-colored image.
[0027] The spectacle lens according to the invention can be
produced from glass and/or plastic.
[0028] The display device according to the invention can comprise
further elements known to a person skilled in the art which are
necessary for its operation.
[0029] It is understood that the features mentioned above and those
yet to be explained below can be used not only in the stated
combinations but also in other combinations or alone, without
departing from the scope of the present invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0030] FIG. 1 is a schematic perspective representation of an
embodiment of the display device according to the invention.
[0031] FIG. 2 is a magnified sectional view of the first spectacle
lens.
[0032] FIG. 3 is a magnified sectional view of the spectacle lens
to describe the coupling-in section.
[0033] FIG. 4 is a representation, magnified again, of the
coupling-in section from FIG. 3.
[0034] FIG. 5 is a magnified sectional representation of the
coupling-out section.
[0035] While the invention is amenable to various modifications and
alternative forms, specifics thereof have been shown by way of
example in the drawings and will be described in detail. It should
be understood, however, that the intention is not to limit the
invention to the particular example embodiments described. On the
contrary, the invention is to cover all modifications, equivalents,
and alternatives falling within the scope of the invention as
defined by the appended claims.
DETAILED DESCRIPTION
[0036] In the following descriptions, the present invention will be
explained with reference to various exemplary embodiments.
Nevertheless, these embodiments are not intended to limit the
present invention to any specific example, environment,
application, or particular implementation described herein.
Therefore, descriptions of these example embodiments are only
provided for purpose of illustration rather than to limit the
present invention.
[0037] In the embodiment shown in FIG. 1 the display device 1
according to the invention comprises a holder 2 that can be fitted
on the head of the user and can be formed e.g. in the manner of a
conventional spectacles frame, as well as a first and a second
spectacle lens 3, 4, which are secured to the holder 2. The holder
2 with the spectacle lenses 3 and 4 can be formed e.g. as sports
glasses, sunglasses and/or glasses for correcting defective vision,
wherein a virtual image can be reflected into the user's field of
view via the first spectacle lens 3, as described below.
[0038] The spectacle lenses 3, 4, and in particular the left-hand
spectacle lens 3, are only described together with the display
device 1 according to the invention by way of example. The
spectacle lenses 3, 4, or at least the left-hand spectacle lens 3,
are in each case formed separately as a spectacle lens 3, 4
according to the invention. The left-hand spectacle lens 3
according to the invention can, naturally, also be formed as the
right-hand spectacle lens.
[0039] As can best be seen from the detailed sectional view of the
first spectacle lens 3 in FIG. 2 (the holder 2 is not represented),
the display device 1 comprises an image-generating module 5, a
control unit 6 and a coupling-in optical system 15. The
image-generating module 5, the control unit 6 and the coupling-in
optical system 15 are represented purely schematically and are
preferably secured to the holder 2. The image-generating module 5
can comprise e.g. a two-dimensional light modulator, such as e.g.
an OLED, CMOS or LCoS chip or a tilting mirror matrix with a
plurality of pixels e.g. arranged in rows and columns. A light
bundle 24 can emerge from each pixel.
[0040] The left-hand spectacle lens 3 comprises a spectacle lens
body 7 with a curved front side 8 and a curved rear side 9, wherein
a coupling-in section 20 is formed on the front side 8 in an edge
area 12 of the first spectacle lens 3 and a coupling-out section 21
is formed in a central area 13 on the front side 8 of the first
spectacle lens 3.
[0041] As shown in the schematic representation from FIG. 2, the
light bundles 24, 24' coming from the image-generating module 5
(which form a total bundle of beams 33) are collimated by means of
the coupling-in optical system 15, enter the first spectacle lens 3
via the rear side 9 and there strike the coupling-in section 20,
which is formed reflective in such a way that it brings about a
deflection of the light bundles 24 such that they are then guided
in the spectacle lens 3 by total internal reflection on the rear
and the front side 9, 8 to the coupling-out section 21. The
coupling-out section 21 is formed reflective and deflects the light
bundles 24, 24' in the direction of the rear side 9 such that they
are coupled out of the spectacle lens 3 via the rear side 9 and run
up to an exit pupil 25. When the holder is fitted on, the user can
position his eye in the area of the exit pupil 25 and thus perceive
the virtual image.
[0042] As can be seen in the magnified representation of the
coupling-in section 20 in FIG. 3, the coupling-in section 20
comprises a plurality of partially reflective facets 26 arranged
next to each other, which serve to deflect the light bundles 24,
24', wherein the facets 26 are buried in the spectacle lens body 7
and arranged next to each other in the direction from the
coupling-in to the coupling-out section 20, 21 in a first area 30
and an adjoining second area 31. The extent of the two areas 30, 31
in the y-direction is chosen such that it corresponds to the extent
of the collimated total bundle of beams 33 striking them. Because
of this extent, the bundles of beams 24 deflected by the facets 26
of the first area 30, after total internal reflection on the rear
side 9, for the guiding of the bundles of beams to the coupling-out
section, strike the second area 31, in which the facets 26 are
arranged for the deflection of the light bundles 24'. Thus, in the
second area 31, there is a superimposition of light bundles 24
already guided by total internal reflection and bundles of beams
24' yet to be coupled in or deflected such that they can also be
guided by total internal reflection.
[0043] In order to be able to satisfy both of these optical
requirements, the buried facets 26 in the second area 31 are
connected in each case by transparent or at least partially
transparent faces 27, which are represented as dashed lines in the
magnified sectional representation of the second area in FIG.
4.
[0044] After total internal reflection on the rear side 9, the
light bundles 24 which are deflected in the first area 30 of the
coupling-in section 20 strike the second area 31 of the coupling-in
section 20. Because of the described transparent or partially
transparent formation of the faces 27, the light bundles 24 run
through the faces 27 and are totally reflected on the front side 8
for the guiding, run through the partially reflective facets 26 in
the second area 31 from behind and strike the rear side 9 again,
with the result that the light bundles 24 are guided in the
intended way to the coupling-out section 21 by further total
reflections on the rear and the front side 9, 8. The light bundles
24' of the collimated total bundle of beams 33, which strike the
facets 26 (here in the second area 31) for the first time for the
coupling-in, are at least partially reflected back to the rear side
9 such that they are then guided to the coupling-out section by
total internal reflection on the rear side 9 and the front side 10.
The second area thus implements both optical requirements (guiding
of the already coupled-in light bundles 24 and coupling-in of the
further light bundles 24'). If the faces 27, as has been usual
until now, were formed as reflective faces, this would result in
undesired stray light. According to the invention, the extent of
the coupling-in section 20 in the direction of the guiding of the
light bundles 24 in the spectacle lens 3 is thus no longer limited
by the fact that an already deflected light bundle 24 must not
strike the coupling-in section 20 again. Thus, even in the case of
a thin spectacle lens 3 and a large image or image field (size of
the image generated by means of the image-generating module 5), a
large eyebox or a large exit pupil 25 can be realized.
[0045] The front side 8 thus forms a first reflecting surface in
the coupling-in section 20 and the rear side 9 thus forms a second
reflecting surface in the coupling-in section 20, wherein the
buried facets 26 are arranged between the two reflecting surfaces.
If the faces 27 in the second area 31 are transparent, as a rule
they are no longer visible. The representation of the faces 27 in
FIG. 3 and in FIG. 4 only serves to better understand the
invention. In the first area 30 the faces 27 connecting the facets
26 can be transparent, partially transparent or reflective.
Furthermore, the facets 26 in the first area can be partially
reflective or reflective.
[0046] To produce the coupling-in section 20, only the depressions
for the facets 26 have to be formed on the front side 8. The facets
26 are then to be provided with the corresponding partially
mirroring layer, wherein, however, the faces 27 are not coated. The
facets 26 are then filled in up to the original radius of the front
side 8, with the result that the front side 8 is also used for the
light guiding by means of total internal reflection in the
described manner in the area of the coupling-in section 20.
[0047] As can be seen in the magnified representation in FIG. 5,
the coupling-out section 21 can comprise several partially
reflective facets 28 arranged next to each other, which are
connected by partially reflective faces 29 or transparent faces 29.
This results in the advantage that a light bundle 24.sub.1 which
strikes a facet 28 in a first area 34 of the coupling-out section
21 is partially deflected towards the exit pupil 25 and partially
24.sub.1' (represented as a dashed line) transmitted. The
transmitted portion 24.sub.1' is totally reflected on the front
side 8, runs through the face 29 in the first area 34 of the
coupling-out section 21 and, after total reflection on the rear
side 9 again, strikes a further partially reflective facet 28 (in a
second area 35 of the coupling-out section 21), at which another
deflection in the direction of the exit pupil 25 takes place.
[0048] A beam path is also possible in which the portion
transmitted through the facet 28 in the first area 34 first runs
through the face 29 and then strikes the next facet 28 in the first
area 34 and is deflected by the latter, as represented
schematically for the bundle of beams 24.sub.2. At the next facet
28 too, a portion can, once again, be transmitted, which then,
after total reflection on the front and the rear side 8, 9 again,
strikes a further facet 28 in the second area 35 and is deflected
by this. In this manner, the coupling-out section 21 acts as a
pupil expander.
[0049] The facets 28 are thus buried facets 28, in the same way as
the facets 26 of the coupling-in section 20. The facets 26, 28 can
extend to the front side 8 or can be spaced apart from the front
side 8.
[0050] The facets 26 of the coupling-in section 20 and the facets
28 of the coupling-out section 21 can be formed such that, in
addition to purely the beam deflection, an imaging effect is also
realized. The shape and position of the facets can be determined
e.g. by means of an optimization calculation. A curved reflective
surface is used as a starting point, which provides the desired
imaging effect and which is then approximated by the facets 26, 28.
The individual facets 26, 28 can be flat or curved. Such a
procedure is described for example in WO 2010/097442 A1 and in WO
2010/097439 A1, wherein the corresponding description, together
with the figures, of these published documents are hereby
incorporated in the present disclosure.
[0051] The reflectivity of the facets 26, 28 can be constant.
However, it is also possible for the reflectivity to increase or
decrease in the direction of the beam guiding.
[0052] In the embodiment described here of the described display
device 1 the coupling of the virtual image into the user's field of
view takes place via the left-hand spectacle lens 3. Naturally, a
coupling-in via the right-hand spectacle lens 4 is also possible.
In addition, the display device 1 can be formed such that images
are reflected in via both spectacle lenses 3, 4. This can be
carried out e.g. in such a way that a three-dimensional image
impression forms.
[0053] The spectacle lenses 3, 4 can be produced e.g. from glass or
from plastic.
[0054] While the invention has been described in connection with
what is presently considered to be the most practical and preferred
embodiments, it will be apparent to those of ordinary skill in the
art that the invention is not to be limited to the disclosed
embodiments. It will be readily apparent to those of ordinary skill
in the art that many modifications and equivalent arrangements can
be made thereof without departing from the spirit and scope of the
present disclosure, such scope to be accorded the broadest
interpretation of the appended claims so as to encompass all
equivalent structures and products. Moreover, features or aspects
of various example embodiments may be mixed and matched (even if
such combination is not explicitly described herein) without
departing from the scope of the invention.
* * * * *